Fix small open issues.

- #33341 already addressed in #36428.
- Fixes #37294: Add text that the shortened format is valid only when the runtime type matches the variable type.
- Fixes #37295: Don't use `ID` in the sample.
- Fixes #37296: Fix nullable warnings. Other issue comments are incorrect.
- Fixes #41748: Change the sample so the constructor is relevant.
- Fixes #42858: Add an explanation on declaring variables in top level statements.

Author: BillWagner

docs/csharp/fundamentals/coding-style/coding-conventions.md

@@ -1,7 +1,7 @@
 ---
 title: ".NET Coding Conventions"
 description: Learn about commonly used coding conventions in C#. Coding conventions create a consistent look to the code and facilitate copying, changing, and maintaining the code. This article also includes the docs repo coding guidelines
-ms.date: 07/27/2023
+ms.date: 01/14/2025
 helpviewer_keyword:
   - "coding conventions, C#"
   - "Visual C#, coding conventions"
@@ -128,7 +128,7 @@ If the divisor is 0, the second clause in the `if` statement would cause a run-t
 
 ### `new` operator
 
-- Use one of the concise forms of object instantiation, as shown in the following declarations.
+- Use one of the concise forms of object instantiation when the variable type matches the object type, as shown in the following declarations. This form isn't valid when the variable is an interface type, or a base class of the runtime type.
 
   :::code language="csharp" source="./snippets/coding-conventions/program.cs" id="Snippet19":::
 
@@ -172,7 +172,7 @@ Call [static](../../language-reference/keywords/static.md) members by using the
 
   :::code language="csharp" source="./snippets/coding-conventions/program.cs" id="Snippet26":::
 
-- Rename properties when the property names in the result would be ambiguous. For example, if your query returns a customer name and a distributor ID, instead of leaving them as `Name` and `ID` in the result, rename them to clarify that `Name` is the name of a customer, and `ID` is the ID of a distributor.
+- Rename properties when the property names in the result would be ambiguous. For example, if your query returns a customer name and a distributor name, instead of leaving them as a form of `Name` in the result, rename them to clarify `CustomerName` is the name of a customer, and `DistributorName` is the name of a distributor.
 
   :::code language="csharp" source="./snippets/coding-conventions/program.cs" id="Snippet27":::
 

docs/csharp/fundamentals/coding-style/snippets/coding-conventions/coding-conventions.csproj

@@ -2,7 +2,8 @@
 
   <PropertyGroup>
     <OutputType>WinExe</OutputType>
-    <TargetFramework>net8.0-windows</TargetFramework>
+    <Nullable>enable</Nullable>
+    <TargetFramework>net9.0-windows</TargetFramework>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <StartupObject>Coding_Conventions_Examples.Program</StartupObject>

docs/csharp/fundamentals/coding-style/snippets/coding-conventions/program.cs

@@ -214,41 +214,41 @@ static void Main(string[] args)
 
             ExampleClass.totalInstances = 1;
 
-            var customers = new List<Customer>
+            var Customers = new List<Customer>
             {
               new Customer { Name = "Jones", ID = 432, City = "Redmond" }
             };
 
             // Check shop name to use this.
-            var distributors = new List<Distributor>
+            var Distributors = new List<Distributor>
             {
               new Distributor { Name = "ShopSmart", ID = 11302, City = "Redmond" }
             };
 
             //<snippet25>
             //<snippet28>
-            var seattleCustomers = from customer in customers
+            var seattleCustomers = from customer in Customers
                                    //</snippet28>
                                    where customer.City == "Seattle"
                                    select customer.Name;
             //</snippet25>
 
             //<snippet26>
             var localDistributors =
-                from customer in customers
-                join distributor in distributors on customer.City equals distributor.City
+                from customer in Customers
+                join distributor in Distributors on customer.City equals distributor.City
                 select new { Customer = customer, Distributor = distributor };
             //</snippet26>
 
             //<snippet27>
             var localDistributors2 =
-                from customer in customers
-                join distributor in distributors on customer.City equals distributor.City
-                select new { CustomerName = customer.Name, DistributorID = distributor.ID };
+                from customer in Customers
+                join distributor in Distributors on customer.City equals distributor.City
+                select new { CustomerName = customer.Name, DistributorName = distributor.Name };
             //</snippet27>
 
             //<snippet29>
-            var seattleCustomers2 = from customer in customers
+            var seattleCustomers2 = from customer in Customers
                                     where customer.City == "Seattle"
                                     orderby customer.Name
                                     select customer;
@@ -257,13 +257,13 @@ orderby customer.Name
             // #30 is in class CompoundFrom
 
             var customerDistributorNames =
-                from customer in customers
-                join distributor in distributors on customer.City equals distributor.City
+                from customer in Customers
+                join distributor in Distributors on customer.City equals distributor.City
                 select new { CustomerName = customer.Name, DistributorID = distributor.ID };
 
             var customerDistributorNames2 =
-                from customer in customers
-                from distributor in distributors
+                from customer in Customers
+                from distributor in Distributors
                 where customer.City == distributor.City
                 select new { CustomerName = customer.Name, DistributorID = distributor.ID };
 
@@ -367,7 +367,7 @@ class CompoundFrom
         public class Student
         {
             public string? LastName { get; set; }
-            public List<int>? Scores { get; set; }
+            public ICollection<int> Scores { get; set; } = default!;
         }
 
         static void Main()
@@ -377,16 +377,16 @@ static void Main()
             // each element in the list contains an inner sequence of scores.
             List<Student> students = new List<Student>
         {
-           new Student {LastName="Omelchenko", Scores= new List<int> {97, 72, 81, 60}},
-           new Student {LastName="O'Donnell", Scores= new List<int> {75, 84, 91, 39}},
-           new Student {LastName="Mortensen", Scores= new List<int> {88, 94, 65, 85}},
-           new Student {LastName="Garcia", Scores= new List<int> {97, 89, 85, 82}},
-           new Student {LastName="Beebe", Scores= new List<int> {35, 72, 91, 70}}
+           new Student {LastName="Omelchenko", Scores = [97, 72, 81, 60]},
+           new Student {LastName="O'Donnell", Scores = [75, 84, 91, 39]},
+           new Student {LastName="Mortensen", Scores = [88, 94, 65, 85]},
+           new Student {LastName="Garcia", Scores = [97, 89, 85, 82]},
+           new Student {LastName="Beebe", Scores = [35, 72, 91, 70]}
         };
 
             //<snippet30>
             var scoreQuery = from student in students
-                             from score in student.Scores!
+                             from score in student.Scores
                              where score > 90
                              select new { Last = student.LastName, score };
             //</snippet30>

docs/csharp/programming-guide/classes-and-structs/snippets/using-constructors/Program.cs

@@ -1,20 +1,25 @@
 //<Snippet1>
 public class Taxi
 {
-    public bool IsInitialized;
+    private string taxiTag;
 
-    public Taxi()
+    public Taxi(string tag)
     {
-        IsInitialized = true;
+        taxiTag = tag;
+    }
+
+    public override string ToString()
+    {
+        return $"Taxi: {taxiTag}";;
     }
 }
 
 class TestTaxi
 {
     static void Main()
     {
-        Taxi t = new Taxi();
-        Console.WriteLine(t.IsInitialized);
+        Taxi t = new Taxi("Tag1345");
+        Console.WriteLine(t);
     }
 }
 //</Snippet1>

docs/csharp/programming-guide/classes-and-structs/snippets/using-constructors/UsingConstructors.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net8.0</TargetFramework>
+    <TargetFramework>net9.0</TargetFramework>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
     <RootNamespace>UsingConstructors</RootNamespace>

docs/csharp/programming-guide/classes-and-structs/using-constructors.md

@@ -1,7 +1,7 @@
 ---
 title: "Using Constructors"
 description: This example shows how a class is instantiated by using the new operator in C#. The simple constructor is invoked after memory is allocated for the new object.
-ms.date: 11/22/2024
+ms.date: 01/14/2025
 helpviewer_keywords: 
   - "constructors [C#], about constructors"
 ---

docs/csharp/tutorials/top-level-statements.md

@@ -100,6 +100,8 @@ Should I use top level statements in all my programs?
 Better not tell you now.
 ```
 
+The code to generate an answer includes a variable declaration in your top level statements. The compiler includes that declaration in the compiler generated `Main` method. Because these variable declarations are local variables, you can't include the `static` modifier.
+
 This code answers the questions, but let's add one more feature. You'd like your question app to simulate thinking about the answer. You can do that by adding a bit of ASCII animation, and pausing while working. Add the following code after the line that echoes the question:
 
 :::code language="csharp" source="snippets/top-level-statements/UtilitiesPassOne.cs" ID="AnimationFirstPass":::